In solid ink imaging systems having intermediate members, ink is loaded into the system in a solid form, either as pellets or as ink sticks, and transported through a feed chute by a feed mechanism for delivery to a heater assembly. A heater plate in the heater assembly melts the solid ink impinging on the plate into a liquid that is delivered to a print head for jetting onto an intermediate transfer member which may be in the form of a rotating drum, for example. In the print head, the liquid ink is typically maintained at a temperature that enables the ink to be ejected by the printing elements in the print head, but that preserves sufficient tackiness for the ink to adhere to the intermediate transfer drum. In some cases, however, the tackiness of the liquid ink may cause a portion of the ink to remain on the drum after the image is transferred onto the media sheet which may later degrade other images formed on the drum.
To address the accumulation of ink on a transfer drum, solid ink imaging systems may be provided with a drum maintenance unit (DMU). In solid ink imaging systems, the DMU is configured to 1) lubricate the image receiving surface of the drum with a very thin, uniform layer of release agent (e.g., Silicone oil) before each print cycle, and 2) remove and store any excess oil, ink and debris from the surface of the drum after each print cycle. Previously known DMU's typically included a reservoir for holding a suitable release agent and capillary forces delivered the release agent to an applicator as needed for applying the release agent to the surface of the drum.
One difficulty faced in drum maintenance systems that utilize an applicator for applying release agent to a transfer surface is uneven saturation of the applicator which may result in potential print quality variation and problems. Problems with uneven saturation are exacerbated by difficulties faced in oil saturation sensing of the applicator. For example, oil saturation sensing of an applicator, however, is prohibitive due to ink and debris buildup in the drum maintenance system over time. That buildup is a byproduct of the print process and results in changes to the characteristics of the applicator and system which potentially may vary from printer-to-printer.